With the rapid development of optical projection industries, optical projection systems are widely used as auxiliary tools in conferences or meetings by companies or individuals. Generally, an optical pen can be directly interacted with the optical projection system in real time by tapping a touch screen or performing an editing operation. Consequently, the optical pen is very convenient to the user.
FIG. 1A is a schematic cross-sectional view illustrating a portion of a conventional optical pen. FIG. 1B is a schematic cross-sectional view illustrating a portion of another conventional optical pen. As shown in FIG. 1A, the conventional optical pen 1 comprises a pen case 10 and an operation module 12. The operation module 12 is disposed within the pen case 10. Moreover, a current switch 11 is further disposed within the pen case 10. The operation module 12 comprises a pen tip 13, a covering part 14 and a supporting part 15. The pen tip 13 includes an infrared light emitting diode (IR LED). The supporting part 15 is coupled with the pen tip 13. The supporting part 15 has some electrical traces (not shown). The covering part 14 is a tube arranged around the pen tip 13 and the supporting part 15. There is a gap between the covering part 14 and the pen case 10. Consequently, the operation module 12 is movable within the pen case 10. During the process of touching a working surface (e.g. a wall surface) by using the optical pen 1, the pen tip 13 is vertical to the working surface. Consequently, a normal counterforce A is generated by the working surface. In response to the normal counterforce A, the pen tip 13 and the supporting part 15 are pushed back. Consequently, the current switch 11 within the pen case 10 is pressed by the supporting part 15 and electrically conducted. Under this circumstance, the IR LED at the pen tip 13 will be turned on, and the subsequent operation procedures will be performed.
As shown in FIG. 1B, the conventional optical pen 2 comprises a pen case 20, an operation module 22, and a current switch 21. The current switch 21 is disposed within the pen case 20. The operation module 22 is also disposed within the pen case 20, and comprises a pen tip 23 and a supporting part 24. The supporting part 24 is coupled with the pen tip 23. In comparison with the optical pen 1 of FIG. 1A, the structure of the supporting part 24 is simpler. The supporting part 24 is an inverted T-shaped structure with a flat base 24a. The periphery of the flat base 24a is in contact with the inner wall of the pen case 20. During the process of touching the working surface by using the optical pen 2, the pen tip 23 is vertical to the working surface. Consequently, a normal counterforce A′ is generated by the working surface. In response to the normal counterforce A′, the pen tip 23 and the supporting part 24 are pushed back. Consequently, the current switch 21 is pressed by the flat base 24a of the supporting part 24 and electrically conducted. Under this circumstance, the IR LED at the pen tip 23 will be turned on, and the subsequent operation procedures will be performed.
Ideally, during the process of touching the working surface by using the optical pen 1 or 2, the pen tip 13 or 23 is vertical to the working surface. In some situations, the pen tip 13 or 23 is not vertical to the working surface. Generally, the gesture of grasping the optical pen is like the gesture of grasping the handwriting pen. That is, the optical pen is usually inclined relative to the working surface.
FIG. 2A is a schematic cross-sectional view illustrating a portion of the conventional optical pen of FIG. 1A, in which the optical pen is inclined relative to the working surface. During the process of touching the working surface, the pen tip 13 is inclined relative to the working surface. Consequently, an inclined counterforce B is generated by the working surface. In response to the inclined counterforce B, the operation module 12 is inclined. Meanwhile, since an external surface of the covering part 14 is in contact with the inner wall of the pen case 10, the movement of the operation module 12 is limited. Moreover, since the pen tip 13 and the supporting part 15 are inclined and pushed back in response to the inclined counterforce B, the current switch 11 is pressed by the supporting part 15 and electrically conducted. Although the optical pen 1 is electrically conducted in response to the inclined counterforce B, some problems may occur. For example, the vertical component of the inclined counterforce B is less than the vertical counterforce A as shown in FIG. 1A. Consequently, it is difficult to trigger the current switch 11. More especially, while the optical pen 1 is horizontal to the working surface to touch the working surface, a horizontal counterforce C is generated by the working surface. Since vertical component of the horizontal counterforce C is very small, the touch sensitivity of the pen tip 13 is impaired.
FIG. 2B is a schematic cross-sectional view illustrating a portion of the conventional optical pen of FIG. 1B, in which the optical pen is inclined relative to the working surface. While the optical pen 2 is horizontal to the working surface to touch the working surface, a horizontal counterforce C′ is generated by the working surface. In response to the horizontal counterforce C′, the pen tip 23 is moved horizontally. Since the supporting part 24 is coupled with the pen tip 23, the supporting part 24 is correspondingly inclined. Meanwhile, the flat base 24a of the supporting part 24 is correspondingly inclined and in contact with the inner wall of the pen case 20 according to the lever principle. Consequently, the current switch 21 is pressed by the flat base 24a of the supporting part 24 and electrically conducted.
From the above discussions about the conventional optical pen 1 or 2, the movement of the operation module 12 or 22 to trigger the current switch 11 or 21 is restricted by the pen case 10 or 20. When the pen tip 13 or 23 of the optical pen 1 or 2 is inclined relative to or horizontal to the working surface to touch the working surface, the touch sensitivity of the pen tip 13 or 23 is impaired. Moreover, a great number of components are disposed within the pen case 10 or 20, the arrangements of the components within the pen case 10 or 20 are dispersed, and the components of the operation module 12 or 22 need to be assembled together one by one. Consequently, the procedures of assembling the operation module 12 or 22 and the optical pen 1 or 2 are very complicated. Moreover, since a portion of the circuitry is disposed within the operation module 12 or 22 and another portion of the circuitry is extended downwardly, the components of the circuitry are dispersed. In other words, the assembling process is complicated, labor-intensive and time-consuming.
Therefore, there is a need of providing an improved optical touch pen in order to eliminate the above drawbacks.